1. Field of the Present Invention
The present invention relates to methods of creating software for controlling complex electronic systems, and more particularly, to a method of creating software for controlling a telecommunications switch.
2. History of the Related Art
FIG. 1 (PRIOR ART) is a block diagram illustrating generally a modern telecommunications switch 102 used in telecommunication systems. The switch 102 includes at least one switch software module 110, switch hardware (HW) 108, a plurality of data inputs 104 to the switch 102, and a plurality of data outputs 106 from the switch 102. The switch hardware 108 allows data to be transferred at very high data rates.
The switch software module 110 provides switch user software 100 with a logical view of the switch 102. A logical view provides a switch user with a plurality of formats each of which indicates how data is received and transmitted within the switch 102, and the type of connection (e.g., point-to-point, point-to-multi-point, multi-point-to-point or multi-point-to-multi-point). Hereinafter, logical views of a switch are referred to as Bearer Service Handlers (BSHs). A BSH also enables a switch user having limited knowledge of the switch hardware 108 to control the switch hardware 108.
Incoming data is received on the data inputs 104 in one specified format and is transmitted in another specified format on the data outputs 106. The switch user software 100 communicates with the switch 102 via a user interface 112. The switch user software 100 specifies that data which is received in a first specified format on one or more of the data inputs 104, is switched to one or more of the data outputs 106 and transmitted in a second specified format. Some examples of specified formats are Asynchronous Transfer Mode--Virtual Path (ATM-VP), Asynchronous Transfer Mode--Virtual Channel (ATM-VC), Synchronous Transfer Mode--64 Kilo-bits per second (STM-64 k), and Synchronous Transfer Mode--2 Mega-bits per second (STM-2M).
ATM is a cell-switch technology based on a fixed length 53-byte cell. All broadband transmissions, whether audio, data, imaging or video, are divided into a series of cells and routed across an ATM network consisting of links connected by ATM switches. Each ATM link comprises a constant stream of ATM cell slots into which transmissions are placed or left idle, if unused. The most significant benefit of ATM is its uniform handling of services allowing one network to meet the needs of many broadband services. ATM technology was selected by the Consultative Committee on International Telephone and Telegraph (CCITT) International Standards Organization in 1988 to implement a broadband integrated services digital network (B-ISDN) in view of its flexibility and suitability for both transmission and switching. In ATM-VP, switching is accomplished by using a Virtual Path Identifier (VPI) value. In contrast, ATM-VC switching is accomplished by using both the VPI value and a Virtual Channel Identifier (VCI) value.
STM is a transport and switching method that depends on information occurring in regular and fixed patterns with respect to a reference such as a frame pattern.
Telecommunication switches are categorized according to the type of switching format the switch hardware supports. For example, switches that support STM format are referred to as "STM switches", and switches that support ATM format are referred to as "ATM switches". In the modern telecommunication industry, switches are created to support a plurality of specified formats. For example, an ATM switch may support both ATM-VP and ATM-VC specified formats, and a STM switch may support both STM-64 k and STM-2M.
FIG. 2 (PRIOR ART) is a block diagram illustrating a telecommunication switch 306 having switch software and switch hardware. Switch 306 comprises switch hardware of type A (SH-A) 314, and switch software units (SS1) 308, (SS2) 310 and (SS-1-2-A) 312. Switch 306 also supports BSHs of types 1 (BSH1) and 2 (BSH2) (not shown). Software units SS1 308 and SS2 310 are dependent upon BSH1 and BSH2, respectively. Software unit SS-1-2-A 312 is dependent upon BSH1, BSH2, and SH-A. User interfaces UI-BSH1 302 and UI-BSH2 304 support BSH1 and BSH2, respectively, and provide the user with the ability to select BSH1 or BSH2 on switch 306.
In the modern telecommunication industry, the software units SS1 308, SS2 310 and SS-1-2-A 312 are created solely for operation on one type of switch (ATM or STM) having a specific type of hardware and implementing at least one BSH. In other words, software units SS1 308, SS2 310 and SS-1-2-A 312 are not created from a Universal Common Software Template (UCST).
There are several disadvantages associated with the current design of software units for telecommunication switches. One such disadvantage results from the repetition of updates or changes for each software unit which is dependent upon a particular type of BSH or switch hardware. For example, changes which are made to the switch hardware must be reflected in updates to each software unit which is dependent upon the switch hardware, and changes which are made to a particular BSH must be reflected in updates to each software unit dependent upon the BSH. Another disadvantage with the current design of software units results from having different groups of developers create the software units for each type of switch. During the creation of the software units, the different groups of developers often use inconsistent terminology, concepts and architecture. The inconsistency in the software units produces increased difficulty in designing switch user software which interfaces with the software units.
It would be a distinct advantage to have a Universal Common Software Template (UCST) capable of creating common software units for a plurality of types of switch hardware and BSHs. The present invention provides such a UCST.